UBSAN: shift-out-of-bounds in pcl812_attach

Status: fixed on 2025/08/28 15:29
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+0ee699f37418ddfc18c1@syzkaller.appspotmail.com
Fix commit: b14b076ce593 comedi: pcl812: Fix bit shift out of bounds
First crash: 384d, last: 374d
Fix bisection: fixed by (bisect log) :
commit 5bfa301e1e59a9b1a7b62a800b54852337c97416
Author: Ian Abbott <abbotti@mev.co.uk>
Date: Mon Jul 7 13:34:29 2025 +0000

  comedi: pcl812: Fix bit shift out of bounds

  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/07/17 upstream (ToT) e2291551827f C [report] UBSAN: shift-out-of-bounds in pcl812_attach
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream UBSAN: shift-out-of-bounds in pcl812_attach comedi -1 syz, C 288 377d 393d 29/29 fixed on 2025/09/04 16:57
linux-6.6 UBSAN: shift-out-of-bounds in pcl812_attach -1 syz, C error 14 374d 384d 0/2 auto-obsoleted due to no activity on 2025/10/01 18:05
linux-5.15 UBSAN: shift-out-of-bounds in pcl812_attach origin:upstream -1 syz, C 90 338d 386d 0/3 auto-obsoleted due to no activity on 2025/11/06 09:23

Sample crash report:
================================================================================
UBSAN: shift-out-of-bounds in drivers/comedi/drivers/pcl812.c:1152:10
shift exponent 8388613 is too large for 32-bit type 'int'
CPU: 1 PID: 4427 Comm: syz.0.16 Not tainted 6.1.144-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x37c/0x400 lib/ubsan.c:321
 pcl812_attach+0x1bc9/0x2340 drivers/comedi/drivers/pcl812.c:1152
 comedi_device_attach+0x515/0x650 drivers/comedi/drivers.c:995
 do_devconfig_ioctl drivers/comedi/comedi_fops.c:851 [inline]
 comedi_unlocked_ioctl+0x5ec/0xe90 drivers/comedi/comedi_fops.c:2131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6965b8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc58f27698 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6965db5fa0 RCX: 00007f6965b8e929
RDX: 0000200000000280 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f6965c10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6965db5fa0 R14: 00007f6965db5fa0 R15: 0000000000000003
 </TASK>
================================================================================

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/13 10:41 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/13 09:52 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/23 18:16 linux-6.1.y 3369c6df2fae e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/23 18:16 linux-6.1.y 3369c6df2fae e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/23 17:01 linux-6.1.y 3369c6df2fae e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/23 17:01 linux-6.1.y 3369c6df2fae e1dd4f22 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/17 06:44 linux-6.1.y f2198ea7eb3e 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/17 06:44 linux-6.1.y f2198ea7eb3e 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/13 11:32 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/13 09:09 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
2025/07/13 09:09 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan UBSAN: shift-out-of-bounds in pcl812_attach
* Struck through repros no longer work on HEAD.